This is for https://fedoraproject.org/wiki/Features/256_Color_Terminals
There is a central script for that feature that is used to enable 256 colors
by adjusting the TERM variable.
However to do that safely it must know the terminal can support this.
The preferred method is to check the $COLORTERM env variable
that many terminals set.
I suggest setting it COLORTERM to 'konsole'
I tested setting that variable manually, from the preferences menu,
where there is an option to add environment variables.
All worked as expected. Note when setting manually (per user) the file:
~/.kde/share/apps/konsole/Shell.profile file
is updated with:
Environment=COLORTERM=konsole,TERM=xterm
thanks,
Pádraig.

Looking closer, I think I'd feel better if you did use one of the KONSOLE_ environment variables after all.
doing otherwise may give a negative impact for kde users who don't use konsole.
I'm going to mark this WONTFIX here in kde-settings, but...
If that's not acceptable to you, please do feel free to re-open.